Wind turbines are designed to convert wind into electricity, by turning a shaft connected to the generator positioned in a wind turbine housing, also known as a nacelle. The rotation of the generator shaft is achieved by wind turbine blades, normally three, that rotate due to the wind. In order to enable optimization of the output power of the wind turbine, the blades may be rotated around their longitudinal axis, also indicated as adjusting a pitch of the blade. In this way, the blades can be used to control the amount of wind power transferred from the wind to the generator.
In conventional wind turbines, a slewing bearing is often used for rotational support of each of the turbine blades relative to the turbine hub. One ring of the bearing is mounted to the hub and the blade is mounted to the other ring of the slewing bearing. Such a slewing bearing may be a ball or roller bearing having a dimension similar to the diameter of the root of the blade (in modern turbines up to 3 meters).
In an attempt to reduce the requirements with respect to stiffness of the typical slewing bearing, an alternative turbine rotor was proposed in GB 2479380. In this patent application, the turbine rotor comprises a hub with a plurality of stubs for connection with a respective blade. Each blade has a pair of spaced apart annular bearings located within a root end of the blade. Each stub protrudes into and is rotatably received within a respective spaced apart bearing and the blades are supported on the hub. A drawback of such a hub is that the stub shafts require a relatively large diameter in order to withstand the loads and the corresponding bearings are also rather large and bulky. As a result, the rotor mass is unacceptably high.